"Right now we are not interested in selling Joao Felix, and soon we will increase his release clause," Vieira told Tuttosport.

"He is one of the best products to have emerged from Portuguese football since Cristiano Ronaldo."

Felix, 19, is under contract until 2023 and his release clause stands at €120m. Portuguese sports newspaper A Bola reported on Sunday that Benfica want to increase that to €200m.

Sporting director Rui Costa recently said Felix would only leave if his release clause was met.

"We will try to keep Joao Felix and other players for as long as possible," he told Tuttosport. "That is the club's policy.

"But we are aware that there are clauses and there are certain players that cannot be held indefinitely in Portugal."

Felix was promoted to Portugal's senior squad last week but did not feature in Friday's goalless draw with Ukraine in Euro 2020 qualifying and is a doubt for Monday's game against Serbia with a foot problem.